package thinkingInJava.containers;

//: containers/ReadOnly.java
//Using the Collections.unmodifiable methods.
import java.util.*;
import static thinkingInJava.YTool.YPrint.*;

public class ReadOnly {
    static Collection<String> data =
        new ArrayList<String>(Countries.names(6));
    public static void main(String[] args) {
        Collection<String> c =
            Collections.unmodifiableCollection(
                new ArrayList<String>(data));
        println(c); // Reading is OK
        //! c.add("one"); // Can't change it
        
        Collections.newSetFromMap(new HashMap<String, Boolean>());
        
        List<String> a = Collections.unmodifiableList(
            new ArrayList<String>(data));
        ListIterator<String> lit = a.listIterator();
        println(lit.next()); // Reading is OK
        //! lit.add("one"); // Can't change it
        
        Set<String> s = Collections.unmodifiableSet(
            new HashSet<String>(data));
        println(s); // Reading is OK
        //! s.add("one"); // Can't change it
        
        // For a SortedSet:
        Set<String> ss = Collections.unmodifiableSortedSet(
            new TreeSet<String>(data));
        
        // Map<String,String> m = Collections.unmodifiableMap(
        //   new HashMap<String,String>(Countries.capitals(6)));
        // println(m); // Reading is OK
        // //! m.put("Ralph", "Howdy!");
        //
        // // For a SortedMap:
        // Map<String,String> sm =
        //   Collections.unmodifiableSortedMap(
        //     new TreeMap<String,String>(Countries.capitals(6)));
    }
} /* Output:
[ALGERIA, ANGOLA, BENIN, BOTSWANA, BULGARIA, BURKINA FASO]
ALGERIA
[BULGARIA, BURKINA FASO, BOTSWANA, BENIN, ANGOLA, ALGERIA]
{BULGARIA=Sofia, BURKINA FASO=Ouagadougou, BOTSWANA=Gaberone, BENIN=Porto-Novo, ANGOLA=Luanda, ALGERIA=Algiers}
 *///:~
